Shaft locking means



Feb. 17, 1959 w. c. STEINMETZ 2,873,848

SHAFT LOCKING MEANS v Filed Feb. 25, 1956 2 Sheets-Sheet 1 {7 INVENTOR},

l v WALTEE C. STEINMETZ) ATV-Y Feb. 17, 1959 w; c. STEINMETZ 2,873,848

SHAFT LOCKING MEANS Filed Feb. 25, 1956 2 Sheets-Sheet 2 J I 'l 4: 1 1

START MOTOR STARTING 5T0 CIRCUIT Fly. 4

INVENTOR; WALT ESE C STEsNM ETZ/ /4& //4%,

United States Patent SHAFT LOCKING MEANS Walter C. Steinmetz, Columbus,Ohio, assignor to lzhe Jeffrey Manufacturing Company, a corporation of01110 Application February 23, 1956, Serial No. 567,160

20 Claims. (Cl. 198232) The instant invention relates to conveyors, andmore particularly to a novel means for preventing rearward rotation of ashaft in aconveyor.

It is the prime object of the instant invention to provide a novel meansfor locking a shaft and preventing rotation thereof.

It is a further object of the instant invention to provide means toprevent rearward rotation of a conveyor head shaft and thereby preventrearward movement of the conveying means.

It is another object of the instant invention to provide a locking meansfor a head shaft of a conveyor, which locking means is automaticallyreleased when the conveyor power means is energized to start rotation ofthe shaft.

It is another object of the instant invention to provide a locking meansfor a conveyor head shaft in which the locking means is automaticallyreleased when the conveyor driving means is energized to start rotationof the shaft, and including speed responsive means connected to theshaft which is operative to render the locking means effective to lockthe shaft when the latter loses speed and stops.

It is still another object of the instant invention to provide a lockingmeans to prevent rotation of a shaft, in which there is provided acontrol circuit which is energized by the release of the locking meansin response to the initial rotation of the shaft, the locking meansbeingoperative to energize the control circuit for actuating means forholding the lockingmeans in released position while the shaft continuesits rotation.

A further object of the instant invention is to provide a locking meansto prevent rearward rotation of a shaft, in which the shaft is providedwith a ratchet wheel and the locking means comprises a pawl for engagingthe ratchet wheel to lock the shaft and thereby prevent rearwardrotation of the shaft, the pawl being released by forward rotation ofthe shaft and operating means for holding the pawl in released positionto permit continued rotation of the shaft in a forward direction. 7

Still another object of this invention is to provide a novel lockingmeans for a shaft in which the shaft is provided with a ratchet wheeland the locking means comprises a pawl adapted to engage the ratchetwheel to lock the shaft against rotation in a rearward direction,-forward rotation of the ratchet wheel releasing the pawl from engagementtherewith and there being provided means for holding the pawl. inreleased position, which means is included in a control circuit which isenergized by the pawl upon release thereof to actuate the holding meansfor retaining the pawl in released position.

Other objects of the invention will appear hereinafter, the novelfeatures and combinations being set forth in the appended claims.

In the accompanying drawings:

Fig. .1 is a partial elevational view showing the head shaft of aconveyor which includes a novel means for preventing rotation of theshaft;

Fig. 2 is an elevational view in section showing the novel shaft lockingmeans of this invention;

Fig. 3, is a plan view in section of the novel shaft locking means takenon the line 33 in Fig. 2;

Fig. 4 is a circuit diagram showing the control. circuit for the novelshaft locking means and its association with the power circuit; and

Fig. 5 is a circuit diagram showing a modification of the controlcircuit illustrated in Fig. 4.

Referring to Fig. 1 of the drawings, there is shown a conveyor N of thevertical elevator type comprising a platform 11 which supports the headshaft 12 of the conveyor 10. The platform 11 also supports a power drivemeans 13 on a laterally extending portion thereof, which may be in theform of an electric motor or the like motive means. The power drivemeans 13 includes a pulley or wheel 14 on which there is entrained apower transmitting chain 15 which drives a pulley or wheel 16 secured onthe shaft 12. The wheel 16 is secured to the shaft 12 and transmitspower to the shaft 12 for driving the conveyor.

The conveyor 10 has an endless chain 17 which is entrained about asprocket wheel 18 secured to the shaft 12. The endless chain 17 is alsoentrained about a second sprocket wheel at the opposite lower end of theconveyor If) (not shown). The chain 17 includes a plurality of buckets19 each secured to a link thereof, which buckets rise on the right sideof the conveyor to convey material to the top thereof, and the buckets19, as they pass around the periphery of the sprocket wheel 18,discharge their contents into a chute or like means and descend ininverted position on the left side of the conveyor as seen in Fig. 1.

It is apparent that the buckets 19 on the right side of the conveyor.are loaded with material whereas the buckets on the left side of theconveyor are empty, so that the added weight on the right side of theconveyor would normally cause the chain 17 to move in a clockwise orrearward direction on the sprocket wheel 18 unless the power drive means13 is operating to move the conveyor chain 17 in a direction to raisethe loaded buckets 19 or if some other means is provided to preventclockwise or rearward rotation of the shaft 12 when the power drivemeans 13 is inoperative. The instant invention contemplates theprovision of a novel locking means adapted to cooperate with shaft 12 tolock the shaft against rearward rotation and prevent downward movementof the loaded buckets 1% when the power drive means 13 is not operativeto drive the shaft 12.

The novel locking means of this invention includes a ratchet wheel 20secured to the shaft 12 and adapted to rotate therewith in acounterclockwise or forward direction when the power drive means 13 isoperative. The teeth 21 on the ratchet wheel 20 face rearwardly and areadapted to be engaged by a pawl 22 to prevent clockwise or rearwardrotation of the ratchet wheel 20 and the shaft 12. As will appearhereinafter, when the power drive means is inoperative the pawl 22projects into the path of the ratchet wheel periphery and engages with atooth 21 thereof to prevent clockwise or rearward rotation, and resiststhe force applied by the loaded buckets 19 attempting to rotate theshaft 12 in a rearward direction.

The pawl 22 is contained within a housing 23 which is supported on theplatform 11. The housing 23 includes a base plate 24 provided at itsforward end with a pair of posts 25 disposed one at each side of thebase plate 24. Each of the posts 25 is bored for the reception of theopposite ends of a transversely extending pin 26, which is fixedlysecured to the posts 25 by set screws 27.

The pawl 22 is bored transversely through the bottom thereof andreceives therein the intermediate portion of the pin 26 which spans thespace between the posts 25.

The pawl 22 pivots on the pin 26 between a position in which it is inengagement with a ratchet wheel tooth 21 as seen in Fig. 2, and aposition in which the pawl 22 iswithdrawn into the housing 23 and isheld in released position out of engagement with the teeth 21 of theratchet wheel 20 (as seen in broken lines in Fig. 2) thereby permittingfree rotation of the shaft 12.

A central portion 28 of the bottom of the pawl surrounding the pin 26 iscut away to provide space for a torsion spring 29 which is wound on thepin 26. One arm 30 of the torsion spring 29 is fixedly secured to thebase plate 24 and a second arm 31 abuts a shoulder 42 on the pawl 22,the force of the spring operating to urge the pawl 22 into engagementwith a tooth 21 'of the ratchet wheel 20. When the power drive means 13is inoperative the pawl 22 is urged into engagement with a tooth 21 ofthe ratchet wheel 20 by the torsion spring 29. When the power drivemeans 13 is energized to operate the conveyor and rotate the shaft 12 ina forward direction. The electric control circuit includes a I.

switch 35 which may be a normally open micro-switch which is closed toenergize the control circuit.

The housing 23, which contains the locking mechanism, has a front wall36 and an intermediate wall 37 formed with apertures 38 and 39,respectively. A plunger 40 is seated in the apertures 38, 39 and extendsbetween the actuator 41 of the switch 35 and a shoulder 42 on the pawl22, located adjacent the cut away portion 28 of the pawl. Thus, when thepawl is pushed away from engagement with a ratchet tooth 21 upon forwardrotation of the ratchet wheel 20 and the shaft 12, the shoulder 42 abutsthe plunger 40 pushing it rearwardly in the apertures 38, 39 andoperating the switch actuator 41 to close the switch 35 and therebyenergize the control circuit for a purpose to be explained hereinafter.

- I The rear face of the pawl 22 is formed with a cutout pocket 45facing rearwardly in the locking mechanism housing 23. One end of aconnecting link 46 is disposed within the pocket 45 and secured to thepawl 22 by a pin 47. The connecting link 46 extends rearwardly from thepawl 22 through an aperture 48 in the front wall 36 and at its rear endis connected to an armature 49 of a solenoid 50 which is bolted to therear wall 52 of the housing 23. The front end of the armature 49 isbifurcated for the reception of the rear end of the connecting link 46.A stud 51 extends between the legs of the bifurcated portion of thearmature 49 and through the end of the connecting link 46 therebyconnecting the armature 49 to the pawl 22.

When the pawl 22 is in engagement with a tooth 21 ofv the ratchet wheel20, as illustrated in Fig. 2, the switch 35 is open and the solenoid 50is dormant. When the power drive means 13 is energized, the shaft 12 andthe ratchet wheel 20 start rotating in a counterclockwise and forwarddirection pushing the pawl 22 away from the teeth 21, thereby releasingthe pawl. The shoulder 42 onthe pawl 22 pushes the plunger 40 rearwardlyto close the switch 35 thereby energizing .the control circuit and thesolenoid 50, the latter drawing the armature 49 rearwardly to pull thepawl 22 completely away from the teeth 21 of the ratchet wheel 20, andas long as the control circuit 55 remains energized, the solenoid 50 isoperative to hold the locking mechanism in released position to permitfree rotation of the shaft 12.

The control circuit is illustrated in Fig. 4, showing its connectionwith the power circuit for the power drive means Energy is delivered tothe power drive means 13 through a plurality of power lines 53 connectedthrough a conventional motor starting means 54. The locking mechanismcontrol circuit 55 is connected across two of the lines 53. It is seenin Fig. 4 that the solenoid 50 and the switch 35 are connected in seriesin the control circuit.

When the power drive means is inoperative and no power is fed throughthe lines 53 the control circuit 55 is likewise not energized, and sincethe solenoid 50 is dormant, the pawl 22 is maintained in its forwardposition in engagementwith a tooth 21 of the ratchet wheel 20 by theforce of the torsion spring 29, operating thereon. When the power drivemeans 13 is energized the shaft 12 and the ratchetwheel 20 startrotating, releasing the pawl 22 from engagement with the tooth 21 andclosing the switch 35 to energize the control circuit 55 and thesolenoid 50 for holding the pawl 22 in released position while the shaft12 is rotating in'the forward or counterclockwise direction.

In a modified. form of the invention (see Fig. 5), the line 56 (Fig. 4)in the control circuit 55 is replaced by the line 57, which includes aspeed responsive plugging switch 58 connected in series to the switch 35and the solenoid 50. Referring to Fig. l, the switch 58 is seen to beconnected to a pulley 59 secured on the shaft 12. A drive chain 60 isentrained on the pulley 59 and on a smaller wheel 61, which is a part ofthe plugging switch 58, to drive the latter. Thus, the plugging switch58 is operated under control of the speed of the shaft 12. The pluggingswitch 58 may be of a conventional form which is speed responsive, tomaintain the switch contacts closed when rotating above a givenrotational speed.

: In operation the plugging switch 58 is normally open maintaining thecontrol circuit 55 de-energized. After the shaft 12 has reached a givenspeed of rotation which is reflected in the rotational speed of theplugging switch 58, the contacts of the plugging switch 58 will close,thereby permitting the control circuit 55 to thereafter operate inresponse to the position of the pawl 22 as previously described.

The instant invention provides a novel locking mechanism to preventrotation of a shaft in one direction, in which rotation of the shaft inthe opposite direction releases the locking mechanism and thereby causesthe energization of a control circuit to operate means for holding thelocking means in released position while the shaft continues itsrotation in the one direction. The control circuit for the novel lockingmechanism is tied to the power drive means for the shaft, so that whenthe power drive means is deactivated the control means is likewisede-energized, whereupon the locking means again operates to lock theshaft against rotation in said opposite direction while the power drivemeans is inactive. As a further feature, the control circuit for thelocking mechanism may include a Speed responsive plugging switch whichis driven by the shaft, and operates the control circuit for holding thelocking means in released position only when the shaft rotates above agiven speed. The plugging switch constitutes a safety feature in thatshould the drive from the power drive means to the shaft failaccidentally, the shaft will lose speed and eventually stop rotating,whereupon the plugging switch will open and render the control circuitof the locking mechanism inoperative to hold the locking means inreleased position, so that the latter will again lock the shaft toprevent rotation thereof in said opposite direction until the shaft isagain rotated in the one direction under control of the power drivemeans.

Obviously those skilled in the art may make various changes in thedetails and arrangement of parts without departing from the spirit andscope of the invention as defined by the claims hereto appended, andapplicant therefore wishes not to be restricted to the precise con-vsjtruction herein disclosed.

Having thus described and shown an embodiment of the invention, what itis desired to secure by Letters Patent of the United States is:

1. In combination with a shaft and power means for rotating the shaft inone direction, means for locking the shaft to prevent rotation thereofin the opposite direction, means operating in response to rotation ofthe shaft in the one direction for releasing the locking means, andmeans operative under control of the locking means for holding thelocking means in released position while the shaft is rotating in theone direction.

2. In combination with a shaft and power means for rotating the shaft inone direction, means for locking the shaft to prevent rotation thereofin the opposite direction, means operating in response to rotation ofthe shaft in the one direction for releasing the locking means, meansfor holding the locking means in released position while the shaft isrotating in the one direction, control means operated by the lockingmeans, and means for operating said holding means in response to theoperation of the control means by the locking means.

3. In combination with a shaft and power means for rotating the shaft inone direction, means including a pawl for locking the shaft to preventrotation in the opposite direction, said shaft including means engagedby the pawl and operating in response to rotation of the shaft in theone direction to release the pawl from engagement therewith, means forholding the pawl in released position while the shaft is rotating in theone direction, control means operated by the pawl, and means foroperating said holding means in response to the operation of the controlmeans by the pawl.

4. In combination with a shaft and power means for rotating the shaft inone direction, means for locking the shaft to prevent rotation thereofin the opposite direction, means operating in response to rotation ofthe shaft in the one direction for releasing the locking means, meansfor holding the locking means in released position while the shaft isrotating in the one direction, a control circuit including said holdingmeans, a switch in said circuit operated by the locking means toenergize the circuit upon release of the locking means and to operatethe holding means.

5. In combination with a shaft and power means for rotating the shaft inone direction, means including a pawl for locking the shaft to preventrotation thereof in the opposite direction, said shaft including meansengaged by the pawl and operating in response to rotation of the shaftin the one direction to release the pawl from engagement therewith,means for holding the pawl in released position while the shaft isrotating in the one direction, a control circuit including said holdingmeans, a switch in said circuit operated by the pawl to energize thecircuit upon release of the pawl and to operate the holding means.

6. In combination with a shaft and power means for rotating the shaft inone direction, means including a pawl for locking the shaft to preventrotation thereof in the opposite direction, said shaft including meansengagedby the pawl and operating in response to rotation of the shaft inthe one direction to release the pawl from engagement therewith, meansfor holding the pawl in released position while the shaft is rotating inthe one direction including a solenoid having an armature linked to thepawl, a control circuit including said solenoid, a switch in saidcircuit operated by .the pawl upon release thereof to energize thesolenoid for operating the armature to hold the pawl in releasedposition.

7. In combination with a shaft and power means for rotating the shaft inone direction, a pawl for locking the shaft to prevent rotation thereofin the opposite direction, a ratchet wheel secured to the shaft andengaged by the pawl for locking the shaft, rotation of the ratchet wheelin the one direction releasing the pawl from engagement therewith, meansfor holding the pawl in re- 6 leased position while the shaft isrotating in the one (ii rection control means operated by the pawl, andmeans for operating said holding means in response to the operation ofthe control means by the pawl.

8. In combination with a shaft and power means for rotating the shaft inone direction, means including a pawl for locking the shaft to preventrotation thereof in the opposite direction, a ratchet wheel secured tothe shaft and engaged by the pawl for locking the shaft, rotation of theratchet wheel in the one direction releasing the pawl from engagementtherewith, means for holding the pawl in released position while theshaft is rotating in the one direction including a solenoid having anarmature linked to the pawl, a control circuit including said solenoid,a switch in said circuit operated by the pawl upon release thereof toenergize the solenoid for operating the armature to hold the pawl inreleased position.

9. In combination with a shaft and power means for rotating the shaft inone direction, means including a pawl for locking the shaft to preventrotation thereof in the opposite direction, a ratchet wheel secured tothe shaft and engaged by the pawl for locking the shaft, rotation of theratchet wheel in the one direction releasing the pawl from engagementtherewith, means for holding the pawl in released position while theshaft is rotating in the one direction, a control circuit including saidholding means, a switch in said circuit operated by the pawl uponrelease thereof to energize the circuit and to operate the holdingmeans.

10. In combination with a shaft and power means for rotating the shaftin a forward direction, means including a pawl for locking the shaft toprevent rotation thereof in a rearward direction, a ratchet wheelsecured to the shaft and engaged by the pawl for locking the shaft,rotation of the ratchet wheel in a forward direction releasing the pawlfrom engagement therewith, means for holding the pawl in releasedposition while the shaft is rotating including a solenoid having anarmature linked to the pawl, a control circuit including said solenoid,a switch in said circuit operated by the pawl upon release thereof toenergize the solenoid for operating the armature to to hold the pawl inreleased position.

11. In combination with a shaft and power means for rotating the shaftin a forward direction, means includmg a pawl for locking the shaft toprevent rotation thereof in a rearward direction, a ratchet wheelsecured to the shaft and engaged by the pawl for locking the shaft,rotation of the ratchet wheel a forward direction releasing the pawlfrom engagement therewith, means for holding the pawl in releasedposition while the shaft is rotating, a control circuit including saidholding means, and a switch in said circuit operated by the pawl toenergize the circuit upon release of the pawl and to operate the holdingmeans.

12. In combination with a shaft and power means for rotating the shaftin a forward direction, a pawl for locking the shaft to prevent rotationthereof in a rearward direction, a ratchet wheel secured to the shaftand engaged by the pawl for locking the shaft, rotation of the ratchetwheel in a forward direction releasing the pawl from engagementtherewith, means for holding the pawl m released position while theshaft is rotating control means operated by the pawl, and means for operatmg said holding means in response to the operation of the controlmeans by the pawl.

13. Imcombination with a shaft and power means for rotating the shaft ina forward direction, means including a pawl for locking the shaft toprevent rotation thereof in a rearward direction, said shaft includingmeans engaged by the pawl and operating in response to forward rotationof the shaft to release the pawl from engagement therewith, means forholding the pawl in released position while the shaft is rotating,control means operated by the pawl, and means for operating said holdingmeans in response to the operation of the control means by the pawl.

14. In combination with a shaft and power means for rotating the shaftin a forward direction, a circuit for energizing the power means, meansfor locking the shaft to prevent rotation thereof in a rearwarddirection, means operating in response to forward rotation of the shaftfor releasing the locking means, means for holding the locking means inreleased position while the shaft is rotating, a control circuitconnected to the first said circuit and including said holding means,and a switch in said control circuit operated by the locking means toenergize the control circuit upon release of the locking means and tooperate the holding means, said control circuit being inoperative whenthe power means is not energized.

15. In combination with a shaft and power means for rotating the shaftin a forward direction, a circuit for energizing the power means, meansincluding a pawl for locking the shaft to prevent rotation thereof in arearward direction, said shaft including means engaged by the pawl andoperating in response to forward rotation of the shaft to release thepawl from engagement therewith, means for holding the pawl in releasedposition while the shaft is rotating, a control circuit connected to thefirst said circuit and including said holding means, and a switch insaid control circuit operated by the pawl to energize the controlcircuit upon release of the pawl and to operate the holding means, saidcontrol circuit being inoperative when the power means is not energized.

16. In combination with a shaft and power means for rotating the shaftin one direction, a circuit for energizing the power means, means forlocking the shaft to prevent rotation thereof in the opposite direction,means operating in response to rotation of the shaft in the onedirection for releasing the locking means, means for holding the lockingmeans in released position while the shaft is rotating in the onedirection, a control circuit connected to the first said circuit andincluding said holding means, and a switch in said control circuitoperated by the locking means to energize the control circuit uponrelease of the locking means and to operate the holding means, saidcontrol circuit being inoperative when the power means is not energized.

17. In combination with a shaft and power means for rotating the shaftin one direction, means for locking the shaft to prevent rotationthereof in the opposite direction, means operating in response torotation of the shaft in the one direction for releasing the lockingmeans, means for holding the locking means in released position whilethe shaft is rotating in the one direction, a control circuit includingsaid holding means, a switch in said circuit operated by the lockingmeans to energize the circuit upon release of the locking means and tooperate the holding means, and a speed responsive plugging switch in thecontrol circuit operating under control of the shaft, said pluggingswitch de-energizing the control circuit when the shaft loses speed andstops rotating to render the holding means inoperative for holding thelocking means in released position.

18. In combination with a shaft and power means for rotating the shaftin one direction, means including a pawl for locking the shaft toprevent rotation thereof in the opposite direction, said shaft includingmeans engaged by the pawl and operating in response to rotation of theshaft in the one direction to release the pawl from engagementtherewith, means for holding the pawl in released position while theshaft is rotating in the one direction, a control circuit including saidholding means, a. switch in said circuit operated by the pawl toenergize the circuit upon release of the pawl and to operate the holdingmeans, and a speed responsive plugging switch in the control circuitoperated by the shaft, said plugging switch de-energizing the controlcircuit when the shaft loses speed and stops rotating to render theholding means inoperative for holding the pawl in released position.

19. In combination with a shaft and power means for rotating the shaftin a forward direction, a circuit for energizing the power means, meansfor locking the shaft to prevent rotation thereof in a rearwarddirection, means operating in response to forward rotation of the shaftfor releasing the locking means, means for holding the locking means inreleased position while the shaft is rotating, a control circuitconnected to the first said circuit and including said holding means, aswitch in said control circuit operated by the locking means to energizethe control circuit upon release of the locking means and to operate theholding means, said control circuit being inoperative when the powermeans is not energized, and a speed responsive plugging switch in thecontrol circuit operated by the shaft, said plugging switchde-energizing the control circuit when the shaft loses speed and stopsrotating to render the holding means inoperative for bolding the lockingmeans in released position.

20. In a'conveyor including a shaft supporting a belt, a motor connectedto the shaft for rotating the shaft to drive the belt, a ratchet wheelsecured to the shaft for rotation therewith, a pawl adapted to engage atooth on the ratchet Wheel to prevent rotation of the shaft, said pawlbeing mounted on a pin for oscillation from a position spaced from theratchet wheel to a position in engagement with a tooth on the ratchetwheel, a torsion spring on the pin and abutting the pawl for urging thepawl into engagement with a tooth on the ratchet wheel, a circuit foroperating the motor and supplying power thereto, a control circuitconnected to the first said circuit, said control circuit including aswitch mechanically connected to the pawl for operation of the switch bythe pawl, a solenoid connected to the switch and energized upon closingsaid switch, said solenoid including an armature linked to the pawl,said pawl being released from engagement with the ratchet tooth uponrotation of the ratchet wheel and closing the switch to energize thesolenoid for operating the armature to hold the pawl in releasedposition.

References Cited in the file of this patent UNITED STATES PATENTS

